Insights in the molecular pathogenesis of cancer has facilitated the consideration of gene replacement strategies for the treatment of specific malignancies. The feasibility of this strategy has recently been demonstrated in vivo and in the treatment of patients with lung cancer using adenoviral mediated gene transfer of wild-type p53. It is widely appreciated that molecular defects that occur at high frequency in cancers disrupt normal apoptotic cell death mechanisms. Our findings suggest that the efficacy of these gene replacement strategies will likely be influenced by context dependent variables such as expression of pro-survival molecules. Further, our data suggests that pro-apoptotic members of the bcl-2 family, including bax and bak, may be important mediators of cell death following wild-type p53 gene transfer in cancer cells. This proposal will address the general hypothesis that restored expression of specific death effector pathways will sensitize cancer cells to cell death induction. Aim 1 will examine the utility of dominant acting cell death effectors as potential therapeutic agents. Our initial efforts will focus on bax and bak, dominant acting cell death effectors of the bcl-2 familty and inhibition of survival signaling through the NfkappaB signaling pathway. Aim 2 will evaluate the impact of pro-survival protein expression on the efficacy of cell death induction by death effector molecules. Aim 3 will assess, in tumor tissue sample obtained from the clinical trials described in Project 1, expression of specific death agonists and antagonists and determine rates of apoptosis and proliferation and correlate these parameters with individual response to therapy. Our preliminary studies provide consistent evidence that the molecular manipulation of cell death will provide the basis for the development of effective strategies for the treatment of cancer patients.